/*!
 * Retina.js v1.4.0
 *
 * Copyright 2016 Imulus, LLC
 * Released under the MIT license
 *
 * Retina.js is an open source script that makes it easy to serve
 * high-resolution images to devices with retina displays.
 */

(function() {
  var root = (typeof exports === 'undefined' ? window : exports);
  var config = {
    // An option to choose a suffix for 2x images
    retinaImageSuffix: '@2x',

    // Ensure Content-Type is an image before trying to load @2x image
    // https://github.com/imulus/retinajs/pull/45)
    check_mime_type: true,

    // An option to select some of the img tags to make their image retina.
    // https://github.com/imulus/retinajs/commit/e7930be
    retinaImgTagSelector: 'body img',
    // Resize high-resolution images to original image's pixel dimensions
    // https://github.com/imulus/retinajs/issues/8
    force_original_dimensions: true
  };

  function Retina() {
  }

  root.Retina = Retina;

  Retina.configure = function(options) {
    if (options === null) {
      options = {};
    }

    for (var prop in options) {
      if (options.hasOwnProperty(prop)) {
        config[prop] = options[prop];
      }
    }
  };

  Retina.init = function(context) {
    if (context === null) {
      context = root;
    }
    context.addEventListener('load', function() {
      // https://github.com/imulus/retinajs/commit/e7930be
      var images = document.querySelectorAll(config.retinaImgTagSelector),
        retinaImages = [],
        i,
        image;
      for (i = 0; i < images.length; i += 1) {
        image = images[i];

        if (!image.getAttributeNode('data-no-retina')) {
          if (image.src) {
            retinaImages.push(new RetinaImage(image));
          }
        }
      }
    });
  };

  Retina.isRetina = function() {
    var mediaQuery = '(-webkit-min-device-pixel-ratio: 1.5), (min--moz-device-pixel-ratio: 1.5), (-o-min-device-pixel-ratio: 3/2), (min-resolution: 1.5dppx)';

    if (root.devicePixelRatio > 1) {
      return true;
    }

    if (root.matchMedia && root.matchMedia(mediaQuery).matches) {
      return true;
    }

    return false;
  };


  var regexMatch = /\.[\w\?=]+$/;
  function suffixReplace(match) {
    return config.retinaImageSuffix + match;
  }

  function RetinaImagePath(path, at_2x_path) {
    this.path = path || '';
    if (typeof at_2x_path !== 'undefined' && at_2x_path !== null) {
      this.at_2x_path = at_2x_path;
      this.perform_check = false;
    } else {
      if (undefined !== document.createElement) {
        var locationObject = document.createElement('a');
        locationObject.href = this.path;
        locationObject.pathname = locationObject.pathname.replace(regexMatch, suffixReplace);
        this.at_2x_path = locationObject.href;
      } else {
        var parts = this.path.split('?');
        parts[0] = parts[0].replace(regexMatch, suffixReplace);
        this.at_2x_path = parts.join('?');
      }
      this.perform_check = true;
    }
  }

  root.RetinaImagePath = RetinaImagePath;

  RetinaImagePath.confirmed_paths = [];

  RetinaImagePath.prototype.is_external = function() {
    return !!(this.path.match(/^(https?\:|\/\/)/i) && !this.path.match('//' + document.domain));
  };

  RetinaImagePath.prototype.check_2x_variant = function(callback) {
    var http,
      that = this;
    if (!this.perform_check && typeof this.at_2x_path !== 'undefined' && this.at_2x_path !== null) {
      return callback(true);
    } else if (this.at_2x_path in RetinaImagePath.confirmed_paths) {
      return callback(true);
    } else if (this.is_external()) {
      return callback(false);
    } else {
      http = new XMLHttpRequest();
      http.open('HEAD', this.at_2x_path);
      http.onreadystatechange = function() {
        if (http.readyState !== 4) {
          return callback(false);
        }

        if (http.status >= 200 && http.status <= 399) {
          if (config.check_mime_type) {
            var type = http.getResponseHeader('Content-Type');
            if (type === null || !type.match(/^image/i)) {
              return callback(false);
            }
          }

          RetinaImagePath.confirmed_paths.push(that.at_2x_path);
          return callback(true);
        } else {
          return callback(false);
        }
      };
      http.send();
    }
  };

  function RetinaImage(el) {
    this.el = el;
    this.path = new RetinaImagePath(this.el.getAttribute('src'), this.el.getAttribute('data-at2x'));
    var that = this;
    this.path.check_2x_variant(function(hasVariant) {
      if (hasVariant) {
        that.swap();
      }
    });
  }

  root.RetinaImage = RetinaImage;

  RetinaImage.prototype.swap = function(path) {
    if (typeof path === 'undefined') {
      path = this.path.at_2x_path;
    }

    var that = this;
    function load() {
      if (!that.el.complete) {
        setTimeout(load, 5);
      } else {
        if (config.force_original_dimensions) {
          if (that.el.offsetWidth === 0 && that.el.offsetHeight === 0) {
            that.el.setAttribute('width', that.el.naturalWidth);
            that.el.setAttribute('height', that.el.naturalHeight);
          } else {
            that.el.setAttribute('width', that.el.offsetWidth);
            that.el.setAttribute('height', that.el.offsetHeight);
          }
        }

        that.el.setAttribute('src', path);
      }
    }
    load();
  };


  if (Retina.isRetina()) {
    Retina.init(root);
  }
})();
